Sensor fixed, measurements made at fixed depths - The sensor is at a fixed depth, but measurements are made remotely from the sensor over a range of depths (e.g. ADCP measurements)

Sensor Depth Datum

Sea floor reference - Depth measured as a height above sea floor but converted into a depth relative to the sea surface according to the same datum as used for sea floor depth (applicable to instrument depths not bathymetric depths)

Sea Floor Depth Datum

Instantaneous - Depth measured below water line or instantaneous water body surface

Parameters

BODC CODE

Rank

Units

Short Title

Title

AADYAA01

1

Days

Date(Loch_Day)

Date (time from 00:00 01/01/1760 to 00:00 UT on day)

AAFDZZ01

1

Days

Time(Day_Fract)

Time (time between 00:00 UT and timestamp)

CPHLPR01

1

Milligrams per cubic metre

chl-a_water_ISfluor

Concentration of chlorophyll-a {chl-a CAS 479-61-8} per unit volume of the water body [particulate >unknown phase] by in-situ chlorophyll fluorometer

Open Data supplied by Natural Environment Research Council (NERC)

Aquatracka fluorometer

The Chelsea Instruments Aquatracka is a logarithmic response fluorometer. It uses a pulsed (5.5 Hz) xenon light source discharging between 320 and 800 nm through a blue filter with a peak transmission of 420 nm and a bandwidth at half maximum of 100 nm. A red filter with sharp cut off, 10% transmission at 664 nm and 678 nm, is used to pass chlorophyll-a fluorescence to the sample photodiode.

The instrument may be deployed either in a through-flow tank, on a CTD frame or moored with a data logging package.

Processing and Calibration by the Data Originator

The logged signal in raw counts was transformed to a dark corrected signal by correcting for dark current using a reading in the dark. This signal was then calibrated against chlorophyll a concentration extracted from a culture of Skeletonema costatum and analysed by HPLC.

All four instruments deployed during the Northern North Sea and Southern North Sea experiments (CI Aquatracka #007, #012, #011, #014) were calibrated jointly at the Dunstaffnage Marine Laboratory. The corrected counts from Instruments #007, #011 and #014 were then normalised to Instrument #012 calibration readings using the following quadratic equations:

The calibration algorithm determined for Instrument #012 was then applied to convert corrected counts to chlorophyll concentration.

This algorithm was:

Chlorophyll (mg/m 3 ) = - 0.00747 [Dark Corrected Count]

General Data Screening carried out by BODC

BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.

Header information is inspected for:

Irregularities such as unfeasible values

Inconsistencies between related information, for example:

Times for instrument deployment and for start/end of data series

Length of record and the number of data cycles/cycle interval

Parameters expected and the parameters actually present in the data cycles

Originator's comments on meter/mooring performance and data quality

Documents are written by BODC highlighting irregularities which cannot be resolved.

Data cycles are inspected using time or depth series plots of all parameters. Currents are additionally inspected using vector scatter plots and time series plots of North and East velocity components. These presentations undergo intrinsic and extrinsic screening to detect infeasible values within the data cycles themselves and inconsistencies as seen when comparing characteristics of adjacent data sets displaced with respect to depth, position or time. Values suspected of being of non-oceanographic origin may be tagged with the BODC flag denoting suspect value; the data values will not be altered.

The following types of irregularity, each relying on visual detection in the plot, are amongst those which may be flagged as suspect:

If a large percentage of the data is affected by irregularities then a Problem Report will be written rather than flagging the individual suspect values. Problem Reports are also used to highlight irregularities seen in the graphical data presentations.

Inconsistencies between the characteristics of the data set and those of its neighbours are sought and, where necessary, documented. This covers inconsistencies such as the following:

Maximum and minimum values of parameters (spikes excluded).

The occurrence of meteorological events.

This intrinsic and extrinsic screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC making are not introduced.

PROcesses of Vertical Exchange in Shelf Seas (PROVESS)

Introduction

PROVESS was an interdisciplinary study of the vertical fluxes of properties through the water column and the surface and bottom boundary layers. The project was funded by the European Community MAST-III programme (MAS3-CT97- 0159) and ran from March 1998 to May 2001.

Scientific Rationale

PROVESS was based on the integration of experimental, theoretical and modelling studies with the aim of improving understanding and quantification of vertical exchange processes in the water column, in particular in the surface and benthic boundary layers and across the> pycnocline. PROVESS also explored mechanisms of physical-biological coupling in which vertical exchanges and turbulence significantly affect the environmental conditions experienced by the biota with particular reference to aggregation, flocculation, sedimentation and trophic interactions.

Fieldwork

The experimental phase of the project was carried out at two contrasting sites in the North Sea: the northern North Sea site (NNS) and the southern North Sea site (SNS).

The two sites had the following characteristics:

SNS

NNS

Position

52° 15.0' N, 4° 17.0' E

59° 20.0' E, 1° 00.0' E

Time of year

April-May

September-November

Water depth (m)

16

100

M2 max amplitude (m s-1)

0.75

0.15

Max current (m s-1)

1.0

0.6

Delta T (deg C)

mixed

7-1

Thermocline depth (m)

mixed

35-100

Delta S

1

small

Halocline depth (m)

5-10

cf. thermocline depth

Max wind speed (m s-1)

20

25

Max wave height (m)

5

10

Max wave period (s)

8

10

Internal motion

No

Yes

Sediment

muddy-sand

muddy-sand

Biology

eutrophic

oligotrophic

At both locations measurements were concentrated at a central position with additional measurements being made to estimate horizontal gradients. Moored instruments (including current meters, temperature and pressure sensors, fluorometers, transmissometers, nutrient analysers and meteorological sensors) were deployed between 7 September and 5 November 1998 at the NNS and between 29 March and 25 May 1999 at the SNS. Each experiment was supported by intensive measurement series made from oceanographic ships and involving turbulence dissipation profiler CTD, particle size profilers, optical profilers, benthic sampling and water bottle sampling.

PROVESS Project POLRIG#798

This mooring was also known within PROVESS as 'Rig I'. It was one of a cluster of moorings deployed at the main focus of the Northern North Sea Site in the autumn of 1998. The rig was deployed by FS Valdivia (cruise #174) in September 1998 and recovered by RRS Challenger (cruise #140) in October/November 1998.

Fixed Station Information

Station Name

PROVESS Northern North Sea Site

Category

Offshore area

Latitude

59° 18.00' N

Longitude

1° 0.00' E

Water depth below MSL

110.0 m

PROVESS Northern North Sea Site

Nineteen mooring packages were deployed at PROVESS Northern North Sea site during the cruise Valdivia VA174 in September 1998. The layout of the mooring assemblage was L-shaped. It consisted of an heavily-instrumented site centred close to 59° 20' N, 1° 00'E (Site A with rigs A, B, Ca/b, D, E, Fa/b, G, H, I, J1, J2 and L) and secondary single-rig sites extending up to 40 km north (V and Y) and east (U and X). An addition mooring package, NIOZ or Rig M, was also deployed at Site A during the RV Pelagia PE125 cruise in October 1998.

Rigs Ca/b and Fa/b were two short-term rigs which were recovered at the end of the cruise VA174 and redeployed during the cruise Challenger CH140 in October. All the other rigs were recovered during the cruise CH140 in October-November 1998 apart from rigs H and L which could not be found and rig Cb which was trawled and recovered from Peterhead (Scotland).

The layout of the mooring array was:

Mooring data

The data returned from each rig were as follows:

Rig identifier

Data

A

POLRIG#790

ADCP currentsWater levelNear-bed temperature

B

POLRIG#791

ADCP currentsNear-bed temperature

Ca

POLRIG#792

Near-bed temperature

Cb

POLRIG#808

Rig trawled, no data returned

D

POLRIG#793

CurrentsTemperature, salinity and attenuance

E

POLRIG#794

Currents

Fa

POLRIG#795

Currents

Fb

POLRIG#809

NIOZ

Unknown

Thermistor chain

G

POLRIG#796

Meteorology

H

POLRIG#797

Mooring lost, no data returned

I

POLRIG#798

Surface attenuance, nutrients and chlorophyll

J1

POLRIG#799

Mid-water attenuance, nutrients and chlorophyll

J2

POLRIG#800

Near-bed attenuance, nutrients and chlorophyll

L

POLRIG#801

Mooring lost, no data returned

R

POLRIG#802

Water column temperature

S

POLRIG#803

Water column temperature

U

POLRIG#804

ADCP currentsWater levelNear-bed temperature

V

POLRIG#805

ADCP currentsNear-bed temperature

X

POLRIG#806

Water level

Y

POLRIG#807

CTD data

A total of 352 CTD casts were also collected during the four cruises surveying this area. These include:

Cruise identifier

Cruise dates

No. of CTD casts

FS Valdivia (#174)

05 September - 17 September 1998

168

Dana (#1198)

14 October - 26 October 1998

51

RV Pelagia (#125)

19 October - 30 October 1998

73

RRS Challenger (#140)

21 October - 11 November 1998

60

Additonal data

Complementary meteorological and sea state data for PROVESS Northern North Sea Experiment were obtained from Marine Weather Stations located on Beryl and Frigg oil platforms in the Northern North Sea.